Climate Warm and wet describes the tropical rain forest climate. The average annual temperature is above 20 C; there is never a frost. Rainfall varies widely from a low of about 250cm of rain per year to about 450 cm/year. That means a range from about 8 to 14 feet of rain per year.
World distribution: As you can see from the map to the right, the tropical rainforests are, indeed, located in the tropics, a band around the equator from 23.5� N (the Tropic of Cancer) to 23.5� S (the Tropic of Capricorn) (red lines on map, right). Because the Earth tilts 23.5 degrees on its axis as it travels around the sun, at some point in the year (the solstices, June 22nd in the north, December 22nd in the south) the sun will be directly overhead on one of these lines. At the equinoxes the sun is directly over the equator. Within this band, solar radiation is most intense, and thus the surface of the planet warms the most. The warmth leads to a lot of evaporation, and as warm, moist air rises, it cools, the water condenses, and the water falls back to the earth as rain. Thus, the warmest areas of the planet also tend to be the wettest, and this sets the stage for the tropical rain forest. Not all of the land in the tropics is tropical rainforest. Some areas are too cold (mountaintops), or are too dry (the far side of a mountain range from the ocean gets less rain). In some places there may be a lot of rain, but it falls seasonally and the long dry season prevents a tropical rainforest from developing.
Warm and wet describes the tropical rain forest climate. The average annual temperature is above 20 C; there is never a frost. Rainfall varies widely from a low of about 250cm of rain per year to about 450 cm/year. That means a range from about 8 to 14 feet of rain per year.
World distribution:
As you can see from the map to the right, the tropical rainforests are, indeed, located in the tropics, a band around the equator from 23.5� N (the Tropic of Cancer) to 23.5� S (the Tropic of Capricorn) (red lines on map, right). Because the Earth tilts 23.5 degrees on its axis as it travels around the sun, at some point in the year (the solstices, June 22nd in the north, December 22nd in the south) the sun will be directly overhead on one of these lines. At the equinoxes the sun is directly over the equator.
Within this band, solar radiation is most intense, and thus the surface of the planet warms the most. The warmth leads to a lot of evaporation, and as warm, moist air rises, it cools, the water condenses, and the water falls back to the earth as rain. Thus, the warmest areas of the planet also tend to be the wettest, and this sets the stage for the tropical rain forest.
Not all of the land in the tropics is tropical rainforest. Some areas are too cold (mountaintops), or are too dry (the far side of a mountain range from the ocean gets less rain). In some places there may be a lot of rain, but it falls seasonally and the long dry season prevents a tropical rainforest from developing.